Electric switch using a bridge contact for either single throw or double throw operation



June 19, 1951 M. G. ANDIS 2,557,493

ELECTRIC SWITCH USING A BRIDGE CONTACT FOR EITHER I SINGLE THROW ORDOUBLE THROW OPERATION Filed April 24, 1948 2 Sheets-Sheet l INVENTOR.MHTTMFW 6 l7/V0/5 A TTOIQNE' v;

June 19, 1951 M. G. ANDIS 2,557,493

ELECTRIC SWITCH USING A BRIDGE CONTACT FOR EITHER SINGLE! THROW ORDOUBLE THROW OPERATIDN Filed April 24. 1948 2 Sheets-Sheet 2 INVENTOR.NArT/YEW 6- flaw/5 A TTOP/VE Y5 Patented June 19, 1951 ELECTRIC SWITCHUSING A BRIDGE CON- TACT FOR EITHER SINGLE THROW OR DOUBLE THROWOPERATION Matthew G. Andis, Racine, Wis., assignor to Andis ClipperCompany, Racine, Wis., a corporation of Wisconsin Application April 24,1948, Serial No. 22,966

14 Claims. 1

This invention relates to an electric switch using a bridge contact foreither single throw or .double throw operation.

It is a primary object of the invention to provide a simple, inexpensiveand trouble-free switch for hair clipper use. The switch has, however,other applications and is claimed per so.

More specifically, it is a primary object of the invention to provide aswitch which functions with snap action and acts very positively inmoving between its on and off positions and is firmly retained in anyposition to which it is adjusted.

The invention resides primarily in details of construction which will bebetter understood from the following disclosure thereof.

In the drawings:

Fig. 1 is a fragmentary plane view of the rear end of a hair clipper inwhich a switch embodying my invention is installed.

Fig. 2 is a fragmentary detail view in longitudinal section through myswitch as it appears when installed in a hair clipper.

Fig. 3 is a fragmentary detail view of the inverted cover of the hairclipper, which serves as a case for my improved switch.

Fig. i is a View similar to Fig. 3 showing the switch in inverted planas it appears with the insulation removed.

Fig. 5 is a detail view in perspective showing the separated componentparts of the switch proper.

Fig. 6 is a detail view showing in front elevation the contacts of theswitch as they appear in their ofi position.

Fig. '7 is a View similar to Fig. 6 showing the contacts in their onposition.

Fig. 8 is a fragmentary inverted plan view similar to Fig. 4 showing amodified embodiment of my switch.

Fig. 9 is a view similar to Fig. 6 showing the contact parts of themodified device of Fig. 8.

Fig. 10 is a detail view in perspective of the spring contact used inthe device of Fig. 8.

As is usual, my improved switch comprises a case which, for the purposesof the present disclosure, constitutes the cover ll of an electric hairclipper, the said cover having a cavity at l2 in which the switchmechanism is disposed and a closure I3 for the cavity, such closurepreferably comprising a sheet of fiber Or other dielectrio material. Theentire case Ii constituting the cover of the hair clipper mayconveniently be made of plastic or other dielectric material.

Journaled in the switch case i l is the actuator 0r shaft 54 which isprovided with an operating knob or handle l5 exposed for manipulation bythe operator. Within the cavity E2, the actuator l4 carries a movingswitch contact 16 which may comprise a metallic block having aprojecting arm at H upwardly beveled to an apex at l8 and having atleast one of its lower corners beveled 01f at l9. The rest of the lowerface of the arm is preferably fiat at 2B.

The contact arm ll coacts with a contact cam 22 which comprises adeformed peripheral portion of a generally annular contact spring 23supported by a bracket 24 which is integral therewith and is anchored byscrew 25, which is threaded into the casing II. This screw passesthrough the dielectric closure plate 53, and also serves as a terminalscrew for anchoring the terminal 25 of the insulated supply wire 2'1.The closure plate i3 has a slot at 28 (Fig. 3) through which the fiatpart of terminal 25 enters to a position to be engaged with the bracket24 for electrical connection with the contact spring 23. Clampingpressure of the dielectric plate [3 under the head of screw 25 holds theterminal in place.

Even in the off position in which the movable contactor I1 is shown inFig. 6, the beveled upper surface of the contactor is preferably inengagement with the contact cam 22. It is, however, spaced from thecomplementary cam surface 30 of the opposing contact spring 3!. Thiscontact spring extends arcuately from an integral bracket portion 32fitted within a correspondingly shaped channel 33 in the case I l. Lyingin that channel is the terminal 34 of the output conductor 35 whichleads to the controlled mechanism (such as the hair clipper motor). Theterminal 34 is clamped in engagement with the bracket 32 by thedielectric closure plate l3 which is held by the head of screw 36.

The opposing cams 30 and 22 of the spring contacts 23 and 3! provide arestricted throat into which the movable contact 5'! must enter in thecourse of its movement from its off position, as shown in Fig. 6 to itson position as shown in Fig. '7. In passing through this throat, theapex It at the top of arm ll passes beneath the cam 22 and engages thefar side thereof, whereby it is rigidly retained in its new position.Further movement of the actuator is preferably precluded by the stopshoulder 3? with which the base of block it engages. An opposingshoulder 38 engages the opposite face of the block to define the oifposition of the moving contaotor.

The bevel of the upper surface of the movable oontactor arm llpreferably corresponds to the bevel of the cam 22 so that a broad facecontact is established between these parts in the relative positionshown in Fig. 7. arm 3| is preferably provided beyond its cam surface 30with a horizontal terminal portion 39 which engages the flat lower facewith broad area of contact when the parts are in the posi* tion shown inFig. 7. Since there is considerable resilient resistance of the springring 23 to the movement of the contactor arm i! from the position ofFig. 6 toward the position of Fig. 7, the operation of the switch willrequire sufficient force so that the movable contactor will spring withsnap action from one position to the other as the peak of cam 22 andapex I8 is passed. A similar snap movement develops in the reverseoperation of the switch toward its off position.

By the simple change shown in Figs. 8 to 10, a double throw switch ismade to function similarly. The arm 3H) is shorter than that abovedescribed and has its fiat bearing surface 398 on the bracket side ofits cam portion 300. Otherwise, it functions exactly like the parts 30,31 and 39 of Figs. 6 and 7.

However, the ring 230, in addition to the deformed contact cam 22 has asecond contact cam at 222, and the movable contactor arm Hi], inaddition to its apex l8 and bevel H] has a second bevel at I92 forinteraction with the cam surface 302 of a second contact spring at 312.The cam surface 362 cooperates with the cam 222 to provide a secondthroat which is opened by the upper and lower beveled surfaces of themovable contactor arm HE. A second recess or channel 332, which isunused in Fig. 4, is now employed to carry the mounting portion 322 ofthe added contact spring 3|, thus enabling a second circuit to becontrolled in the second of the throw positions of the movablecontactor.

In both constructions, the ring 23 or 230 is subjected to a certainamount of torsional thrust tending to oscillate it with the actuatorduring actuator movement. To resist this, without the expense of addedparts or an exceptionally rigid mounting, I desirably form the casing iito provide shoulders at 42 and 43 against which lugs :34, 55,respectively, engage to absorb this thrust as shown in Figs. a and 8.

The result, using either of the constructions disclosed, is anexceptionally rugged, smoothly operable, and yet inexpensive, snapaction switch with long life and few parts. It will be noted that thecontacts are self-cleaning due to their wiping movement to and fromengagement.

I claim:

1. A switch comprising the combination with a mounting, of a resilientannular ring contact carried thereby and provided with a contact camsurface, an oscillatory actuator extending through the mounting andprovided with a movable contactor adapted for arcuate movement alongsaid annular contact and having a cam opposed to the cam first mentionedand coacting therewith, a contact arm carried by said mounting inaxially spaced relation to said annular contact and having a cam surfaceopposed to the cam surface first mentioned, said movable contactor beingadapted to displace said resilient ring by moving between the camsurfaces of said ring and said arm.

2. A switch comprising the combination with a casing and an actuatoroscillatable therein, of an oscillatable contact arm carried by theactuator and provided with opposed beveled faces, and a pair of opposedcontact springs havin Similarly, the spring complementary beveled facesproviding a resiliently yieldable throat through which said arm ismovable in the course of actuator oscillation, one of said springsextending arcuately about said actuator and having a support mounting atone side only, the'beveled face of said one spring being arcuatelyoffset from said support mounting whereby the spring is resilientlyyieldable between said support mounting and said beveled face, the otherof said springs being connected to the opposite side of the casing.

3. A moving contactor comprising oppositely beveled surfaces and a flatface adjoining one of said surfaces, and a pair of opposing contacts atleast one of which is resilient, said contacts having inclined facesproviding a throat of less thickness than the actuator and into whichsaid actuator is movable to displace the resilient contact, one of saidcontacts being provided beyond said throat with a substantially flatface complementary to that of the movable contactor.

4. The combination set forth in claim 3 in further combination with anadditional stationary contact having a beveled surfac and a fiat facecontiguous thereto, the movable contactor having an additional bevel forcoacting with the contactor last mentioned.

5. A switch of the character described comprising an oscillatoryactuator, a resilient ring encircling the actuator, a movable contactmember connected with the actuator and disposed within said ring, saidring having stop means limiting the oscillation of said member, and anarm projecting from said member across one side of said ring, the ringand arm having opposing beveled cam faces for interaction between twoextreme positions of said member respecting said ring, and at least onecontact arm positioned to be engaged by the arm of said member in one ofits extreme positions'aforesaid, together with cas ing means forenclosing and mounting said actuator and ring and arm last mentioned.

6. In a switch, the combination with a casing having a switch cavity anda resilient ring disposed therein and provided with an outwardlyprojecting bracket arm mounted on said casing, of peripherallyinteracting means on the casing and ring opposing torsional displacementof the ring, said means having freedom of relative axial movement toaccommodate the resilient yielding of the ring, an oscillatory actuatormounted in the casing and extending into the ring, and a contactorcarried by the actuator, said contactor and ring having coacting contactcam surfaces.

7. The combination set forth in claim 6 in further combination with acontact spaced from the ring and having an opposing beveled contactsurface, the surface of the contact and the beveled surface of the ringproviding a throat into which said contactor must be forced by saidactuator in the oscillation of the latter.

8. In a switch, the combination with a casing having a cavity providedwith opposing shoulders, of a ring comprising a resilient contactdisposed within the cavity and having a bracket arm connected with thecasing at one side of the cavity and having lugs engageable with theshoulders to transmit to the casing any torsional thrust to which thering is subject, said rin having an axially deformed cam portion remotefrom its bracket arm, an oscillatory actuator mounted in thecasing andextending into the ring, a contactor mounted on the actuator andcomprising an arm having a cam surface 00- acting with the said camsurface of the ring,

said ring and actuator having coacting parts limiting the oscillatorymovement of the contactor, and a resilient arm provided with bracketmeans supporting it from said casing, said arm having a contact surfacespaced from that of the ring and constituting therewith a throat intowhich said contactor is movable to bridge electrically between the ringand the contact arm last mentioned.

9. The device of claim 8 in which the contact arm last mentioned and thecontactor have substantially flat faces which abut when said contactorhas passed said throat in one direction, the contactor being free ofconnection with said contact arm when it has passed said throat in theopposite direction of actuator oscillation.

10. A switch comprising the combination with a casing providing a cavityand a dielectric closure plate for said casing, of screws connecting theclosure plate with the casing, electrical switch contacts disposedwithin the cavity and having. bracket means supported on the casing andconfined by the closure plate, said screws comprising terminal screwsfor establishing electrical connections to said brackets subject to theclamping pressure of said closure plate and said screws.

11. The device of claim 10 in which the closure plate is provided withan opening adjacent one of said screws adapted to receive an electricalterminal for connection with the screw last mentioned."

12. An electric switch comprising an annular spring contact having apair of angularly spaced cams, a movable contactor having oppositelybeveled surfaces and an intervening apex having rectilinear facesmounted for relative movement in a range in which said apex may bepassed beneath the respective spaced cams, and separate contacts withwhich said contactor engages ,fi-n the respective positions which itreaches after having passed the respective cams.

13. A switch comprising the combination with a casing having a cavity,of an actuator extending into said cavity and provided externally with ahandle, a spring contact extending arcuately about said actuator withinthe cavity and provided with a bracket mounted on the casing at one sideof the cavity and with a cam apex having rectilinear faces at the otherside of the cavity, a cooperating contact spring mounted on the casingat the side of the cavity last mentioned and having a beveled camsurface opposed to that of the first mentioned contact, the saidsurfaces together comprising a throat which may be opened by theyielding of the respective contacts, and a contactor carried by theactuator and having an electrically conductive portion disposed betweenthe spring contacts and oscillatory through said throat and of such dimensions as to engage both of said spring contacts for establishing abridging connection therebetween upon traversing said throat, the saidcontactor having oppositely beveled rectilinear faces engaging therespective contacts, said actuator and one of said contacts havingcomplementary substantially flat faces engaged at one side of saidthroat.

14. A switch including a mounting and an oscillatory actuator providedwith a contactor, spaced fiat springs secured in said mounting andformed to provide cam surfaces comprising spaced contacts fixed againstrotation but yieldable in a direction normal to the arc of movement ofthe contactor, one of said springs being shaped in annular form aboutsaid oscillatory actuator and having a support mounting angularl-yoffset from its contact whereby said contact is positioned to yieldinglybear against the contactor, said contactor being dimensioned to contactthe other spring only when aligned with its cam surface.

MATTHEW G. ANDIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,153,505 Levison Sept. 14, 19151,262,320 Freeman Apr. 9, 1918 2,023,146 Parker Dec. 3, 1935 2,071,099Zuckerman Feb. 16, 1937 2,077,472 Gottlieb Apr. 20, 1937 2,170,711Edwards et al Aug. 22, 1939 2,186,638 Hall Jan. 9, 1940 2,415,858Youhouse Feb. 18, 1947

